CPT® Code 93356

Add-On Code

Last Updated: February 2026 | Verified for 2026 AMA, CPT & CMS Guidelines

Quick Reference:

• What CPT 93356 means: CPT +93356 is an add-on code for myocardial strain imaging using speckle tracking-derived assessment of myocardial mechanics. It reports the additional acquisition/analysis and interpretation required to quantify myocardial deformation (most commonly left ventricular global longitudinal strain (GLS)) in conjunction with a standard echocardiogram. [5]
• Never billed alone: By CPT instruction, 93356 is listed separately in addition to an eligible echocardiography service and is not a standalone diagnostic test. ASE coding guidance reinforces that it is reported only when performed and documented as part of a qualifying echo session. [1][5]
• Report once per imaging session: CPT guidance (summarized in authoritative coding guidance) limits +93356 to one unit per echocardiography imaging session, even if multiple strain parameters or repeated measurements are obtained during that same study. [1][5]
• Clinical value and common indications: Strain imaging can identify subclinical LV dysfunction and provide prognostic information beyond ejection fraction in selected conditions (for example, cardio-oncology surveillance or cardiomyopathy phenotyping). However, payer coverage varies and many commercial policies classify routine use as investigational/not medically necessary for broad indications. [2][3]
• Modifier essentials: Use modifier 26 or TC only if required by the payer’s claims processing rules for the underlying echo billing arrangement; do not add modifier 59 “to force payment” because +93356 is defined as an add-on to the primary echo service. When denials occur, they are commonly driven by payer “global/bundled” policy logic rather than NCCI edits. [1][4]
• Documentation and retention are audit-critical: The medical record should show (a) why strain was needed, (b) that speckle-tracking strain analysis was performed, (c) the quantitative result(s) and interpretation, and (d) that the images/measurements are retained as part of the echocardiography record. IAC standards require robust archiving and complete reporting for echo studies. [6]

CPT +93356 is now a routine capability in many echo labs, but it remains a high-variance billing item because

1. it is an add-on with strict pairing rules,
2. payer coverage policies are inconsistent and often restrictive, and
3. auditors expect the record to show that the strain analysis was performed, interpreted, and clinically relevant to the encounter—not merely generated by software.

This 2026-focused guide explains how to report +93356 compliantly, how to align documentation with payer reality, and how to reduce denials by making the claim and the echo report tell the same story.

1. Clinical Definition and Procedure Scope

CPT +93356 is defined as myocardial strain imaging using a speckle tracking-derived assessment of myocardial mechanics and is reported list separately in addition to codes for echocardiography imaging. The key operational meaning is that 93356 represents incremental physician/clinical work beyond a standard echocardiographic study: acquiring suitable image loops for tracking, performing or supervising strain analysis, confirming tracking quality, interpreting quantitative outputs (most commonly GLS), and integrating those results into the final echo interpretation. [5]

What strain measures: Strain imaging quantifies myocardial deformation (change in length relative to baseline) and can be expressed as global and segmental parameters. In practice, the most frequently reported parameter is left ventricular global longitudinal strain because it is widely used for early dysfunction detection and longitudinal follow-up. The strain result should not appear as an isolated number; it should be interpreted in clinical context and reconciled with ejection fraction, chamber sizes, wall motion, valvular findings, and hemodynamics when available.

What 93356 does not represent: +93356 is not a replacement for transthoracic echocardiography, not a substitute for a comprehensive echo report, and not a “software fee.” Coding authorities emphasize that it is billed when the additional strain work is actually performed and documented as part of an eligible echo encounter. ASE’s coding FAQ material is commonly used by echo labs and billing teams to operationalize this add-on logic. [1]

Compliance boundary: If the report does not document that speckle-tracking strain analysis was performed and interpreted (with quantitative results and clinical interpretation), payers can reasonably conclude that +93356 is not supported—even if the echo system can generate strain automatically. Documentation must demonstrate professional interpretation and clinical relevance. [1][6]

2. Eligible Base Echocardiography Codes and Add-On Rules

CPT rules require that +93356 be reported in addition to an eligible echocardiography imaging code performed in the same session. Authoritative coding guidance describes the pairing logic and reinforces that it is reported only once per imaging session. [1][5]

Practical pairing concept: The base code describes the standard echocardiographic exam (resting TTE or stress echocardiography). +93356 describes the incremental strain mechanics analysis performed within that same exam. If the base echo is not performed (or not billed), +93356 is not reportable.

One unit per session: Even when multiple deformation parameters are produced (for example GLS plus right ventricular strain, or multiple views), the add-on code is generally reported only once for the imaging session when strain imaging is performed as part of that study. ASE and AMA coding guidance are the practical anchors used by billing teams to apply this rule. [1][5]

Important operational implication: If strain is performed on both a resting and stress component that are billed as distinct echo services, the record must make clear whether strain was performed as part of one imaging session or two distinct sessions. Do not assume that “more data” automatically supports more units; the unit rule is session-based and payer interpretation can be strict. When in doubt, document the session structure clearly and align billing conservatively with the most defensible interpretation. [1]

3. Clinical Use Cases and When Strain Adds Defensible Value

Myocardial strain imaging is used to detect dysfunction that may not yet be reflected by ejection fraction or visual wall motion assessment. In appropriately selected patients, it can add diagnostic and prognostic information. However, billing defensibility depends on whether the indication is credible and whether the result is integrated into management reasoning. This matters because major payers explicitly evaluate strain as investigational for broad routine use and may deny coverage without case-specific medical necessity. [2][3]

3.1 High-yield, payer-relevant use cases

• Cardio-oncology surveillance: Strain may be used to monitor for early LV dysfunction during potentially cardiotoxic therapy. In this setting, documentation should be explicit: the cancer therapy context, baseline status, and how strain results will inform monitoring intensity or cardioprotective management. Because some commercial policies deny routine chemo surveillance strain as not medically necessary, the record must be unusually clear about patient-specific risk and intended clinical action. [2][3]
• Cardiomyopathy phenotyping and early dysfunction: In selected cardiomyopathies or borderline LV function, strain can help characterize subclinical impairment and track interval change when symptoms or therapy changes occur.
• Valvular disease with discordant findings: When symptoms, EF, and valve severity appear discordant, strain may provide incremental functional information. Documentation should clarify why standard metrics were insufficient for decision-making in that case.
• Serial monitoring where a change is expected: Strain is most defensible when the clinician anticipates that the result may change management (for example, medication adjustment, therapy modification, closer surveillance), rather than as a routine extra measurement. Payer reality: The strongest clinical arguments for strain do not automatically translate into coverage. Major commercial medical policies may categorize strain imaging as investigational for many indications, so medical necessity documentation must be case-specific and management-linked rather than general statements about “better sensitivity.” [2][3]

4. Medicare and Commercial Coverage Reality

There is no single universal coverage rule for +93356 across payers. Instead, payment behavior is shaped by a combination of CPT’s add-on status, local claims processing conventions, and plan medical policies. In practice, two realities dominate:

• Medicare claims behavior often follows standard echocardiography “reasonable and necessary” logic, with +93356 processed when billed correctly as an add-on service and supported by documentation; and
• Commercial payer coverage frequently relies on explicit medical policies that may define myocardial strain imaging as investigational or not medically necessary for routine use, leading to denials even when the echo itself is covered. [2][3]

4.1 Commercial policies: why denials occur

Anthem’s medical policy on myocardial strain imaging is an example of a plan-level framework that reviews the evidence base and determines whether strain is medically necessary for specific indications. Such policies commonly recognize clinical interest but still deny routine coverage due to plan determinations about outcome evidence thresholds. [2]

Blue Cross Blue Shield of Kansas publishes a similarly explicit policy posture on myocardial strain imaging, describing it as experimental/investigational for broad indications. Whether or not a particular clinical scenario seems compelling, the plan policy can drive denial unless an exception pathway applies. [3]

4.2 “Bundled/global” denials even when the code is valid

Another common denial mechanism is not clinical policy but payment policy: some payers treat +93356 as “global” to standard echo codes and deny it as included, even though CPT defines it as an add-on. The MVP provider policy document is an example of payer-level payment policy language that can create automatic denials. [4]

This is why denial management for +93356 often requires two parallel strategies:

• Clinical medical necessity strategy: show why strain mattered for this patient; and
• Coding/payment strategy: show that +93356 is a CPT-defined add-on performed and documented in the encounter (supported by authoritative coding references). [1][5]

5. Modifier Usage (26, TC, 59) and Common Claim Pitfalls

Modifier mistakes are a frequent source of avoidable denials. The safest approach is to treat +93356 as what it is: an add-on component of a qualifying echo encounter. ASE coding FAQs and AMA CPT Assistant guidance are commonly used to interpret how the code is reported and how it is expected to function in claims. [1][5]

5.1 Modifier 26 and TC

The professional/technical component split is fundamentally driven by the setting and by the billing entity’s role in the service. In split-billing arrangements (for example, a facility bills the technical component of the base echo and a physician bills the professional interpretation), modifiers -26 and -TC are applied to the base echo according to standard radiology/cardiology billing conventions. For +93356, payer processing rules can vary, but authoritative echo coding guidance is often cited in practice to support that the strain add-on is reported as part of the physician’s interpretation work when performed and documented, rather than being treated as a separate standalone technical test. [1]

Practical rule: align the modifiers with how the underlying echo is billed in your environment, and avoid improvising modifier usage solely to counter denials. When denials occur, first confirm whether the payer’s policy is a clinical investigational policy or a payment policy (global/bundled) issue. [4]

5.2 Modifier 59

Modifier 59 is intended to identify a distinct procedural service, such as a separate session, separate site, or separate encounter, when a payer edit would otherwise bundle services. It is generally not appropriate to append modifier 59 to +93356 simply because the payer denied it. Because +93356 is defined as an add-on to an eligible echo service, it is inherently part of the same session and should not require 59 “to make it separate.” ASE guidance is frequently used to support this operational interpretation. [1]

High-risk pattern: Using modifier 59 to “force payment” for +93356 without a truly separate encounter is a classic audit trigger. If your denial is driven by a payer’s global/bundled payment policy, modifier 59 does not fix the underlying policy and can increase audit risk. [4]

6. ICD-10 Diagnosis Linkage Examples

CPT +93356 is only as defensible as the medical necessity for the underlying echocardiogram and the incremental necessity for strain analysis. Diagnosis coding should explain why an echo is needed and, when relevant, why strain adds value in this patient. Payers that view strain as investigational frequently scrutinize the diagnosis/indication narrative and may require more than a broad screening diagnosis. [2][3]

The following examples are illustrative (not payer guarantees). Always align diagnosis selection with the clinician’s documentation:

• Heart failure / suspected LV dysfunction: I50.- series when clinically supported, particularly when symptom change or therapy adjustment is being evaluated.
• Cardiomyopathy evaluation: I42.- series when echo is ordered to characterize myocardial function and structure.
• Ischemic heart disease evaluation: I25.- series when the echo indication relates to suspected or known ischemic disease and functional assessment is needed.
• Cardio-oncology context: Encounters involving antineoplastic therapy or surveillance should be coded to reflect the oncology treatment context when documented (for example, encounter-based codes used in oncology follow-up workflows), paired with cardiovascular diagnoses if present. Because coverage policies may deny routine strain surveillance, the note should explicitly document the therapy risk, baseline status, and intended action based on strain results. [2][3]
• Abnormal prior test prompting advanced functional assessment: diagnosis coding should reflect the actual abnormality and clinical concern documented in the record (not a generic “screening” rationale). Avoid “screening-style” narratives: If the record reads like a routine screening service (no symptoms, no management implications, no risk justification), commercial payers that treat strain as investigational are more likely to deny. Medical necessity should be tied to patient-specific risk or a decision point. [2]

7. Frequency, Repeat Testing, and Medical Necessity

CPT add-on logic is clear that +93356 is reported once per imaging session. The bigger practical question is repeat testing across time. Neither CPT nor coding guidance is intended to create “routine schedule” coverage; payers expect that repeated echocardiography (and therefore repeated strain) reflects a change in symptoms, treatment, risk status, or a defined monitoring program justified in the medical record. ASE coding guidance and AMA CPT Assistant discussions emphasize that the add-on is reported when performed and documented as part of a qualifying echo. [1][5]

7.1 Repeat strain: what documentation should show

• Baseline vs follow-up purpose: clearly identify whether this exam is baseline characterization or interval monitoring.
• What changed: symptoms, medication changes, new therapy exposure, new abnormality, or a defined monitoring milestone.
• How results will be used: what clinical action is anticipated if strain worsens (for example additional cardiology evaluation, therapy modification, cardioprotective strategies, or closer surveillance).

This is especially important in cardio-oncology surveillance because some commercial payers explicitly deny routine strain imaging for chemo monitoring. If a plan policy is restrictive, the record must demonstrate why this patient is not a routine case and why the incremental information is clinically necessary. [2][3]

8. Documentation Standards and Image Retention

Documentation for +93356 must support both coding and clinical integrity: that strain imaging was performed, that it yielded interpretable quantitative results, and that those results were interpreted in context. In addition, echo labs must retain a complete imaging record. The IAC adult echocardiography standards provide an authoritative benchmark for echo documentation and retention expectations. [6]

8.1 Minimum documentation elements (audit-proofing)

• Indication: why strain imaging was performed in addition to the base echo (patient-specific reason, not generic “for more data”).
• Technique statement: documentation that speckle-tracking strain analysis was performed (for example, “2D speckle-tracking GLS measured”).
• Quantitative results: GLS value (and other strain measures if reported), including interpretive context (normal/abnormal based on lab standards, and comparison to prior when applicable).
• Quality/limitations: if tracking quality was limited (suboptimal image quality, arrhythmia, poor endocardial definition), document limitations and interpret results accordingly.
• Integrated interpretation: explain how strain relates to EF and other echo findings; strain should be part of the impression when it influences assessment.
• Signature and report finalization: signed/attested interpretation consistent with your institutional and payer standards.

8.2 Image and data retention

Strain analysis is not only a number; it is derived from stored cine loops and tracking overlays/curves that must be retained as part of the echocardiography record. IAC standards require that echo laboratories maintain systems and processes supporting complete acquisition, reporting, and retention of echocardiography data. In practical terms, you should be able to retrieve:

• the cine loops used for speckle-tracking,
• the strain measurement outputs (curves/bulls-eye maps as used in your lab), and
• the finalized interpretive report tying strain to clinical interpretation.

When payers request records, they frequently ask for the complete echo report and supporting documentation; the ability to reproduce the strain evidence can materially strengthen appeals, especially when a policy denial is being challenged on medical necessity grounds. [6]

Documentation mismatch denial: A frequent post-payment vulnerability is a claim that includes +93356, while the echo report contains no strain section, no quantitative value, or no interpretive integration. This mismatch is preventable by templating and internal QA. [6]

9. Common Denials, “Global” Bundling Policies, and Appeals Strategy

Denials for +93356 cluster into two categories: (1) coverage/medical policy denials (investigational/not medically necessary) and (2) payment policy denials (bundled/global to the base echo). Your response strategy depends on which category applies.

9.1 Coverage/medical policy denials (investigational / not medically necessary)

Anthem’s myocardial strain imaging medical policy and the BCBS Kansas policy are examples of explicit coverage frameworks that can deny routine use, including in chemo surveillance contexts. Appeals in this category generally require:

• clear patient-specific risk and indication,
• documentation that results affect management, and
• any plan-defined exception pathway documentation if available.

Because these denials are policy-based, the goal is not to “prove the code exists,” but to show why this patient meets a medically necessary exception under the plan’s own criteria or why the plan’s policy permits coverage in this clinical context. [2][3]

9.2 Payment policy denials (global/bundled to base echo)

MVP’s provider policy document illustrates a different denial mechanism: denial because the payer treats +93356 as included with comprehensive echo codes. In these cases, the most effective appeal package usually includes:

• a copy of the finalized echo report showing strain was performed and interpreted,
• a brief coding rationale citing authoritative coding sources that describe +93356 as an add-on code when performed, and
• the clinical indication demonstrating that strain was not incidental but requested/performed for a defined reason.

Success depends on payer rules: some plans will uphold the bundling policy regardless of documentation; others may allow exceptions or correct misprocessing. The key compliance point is to avoid modifiers or creative coding intended to bypass bundling; that creates audit exposure without reliably improving payment. [4][1]

10. Comparison Table: +93356 vs Common TTE/Stress Echo Codes

11. Real-World Clinical Scenarios

Scenario 1: Cardio-oncology baseline evaluation with a management plan

Setting: Outpatient cardiology / cardio-oncology clinic.

Service: Complete TTE performed with speckle-tracking GLS because the patient is initiating potentially cardiotoxic therapy and has cardiovascular risk factors.

Coding logic: Bill the appropriate TTE code and add +93356 only if strain was performed and documented (quantitative GLS and interpretation integrated into the report). [1][5]

Documentation tip: State how GLS will be used (baseline comparator, escalation of monitoring if GLS declines, cardioprotective strategy considerations). This is important because major commercial policies may deny routine chemo monitoring strain without strong patient-specific necessity. [2][3]

Scenario 2: Heart failure symptoms with borderline EF where strain clarifies function

Setting: Cardiology practice.

Service: TTE shows borderline EF and equivocal regional motion; GLS performed to quantify LV function and support treatment intensity decisions.

Coding logic: Add +93356 if strain analysis is performed and reported as part of the study; report once for the session. [1]

Documentation tip: Include a clear “why strain” statement (e.g., discrepancy between symptoms and EF, need for quantitative baseline for follow-up).

Scenario 3: Denial as “bundled/global” despite proper performance

Setting: Commercial payer claim.

Service: TTE with strain performed and reported; payer denies +93356 as included with base echo.

Appeal approach: Submit the signed report showing strain section and GLS value; include a short coding rationale referencing authoritative coding guidance describing +93356 as an add-on when performed; avoid modifier 59 strategies unless there is truly a separate session. [4][1][5]

Scenario 4: Audit vulnerability from missing strain documentation

Setting: Echo lab with automated strain software.

Problem: +93356 billed, but the final report contains no GLS value and no interpretation.

Risk: High risk for post-payment recoupment because the claim is not supported by the report; IAC standards emphasize complete reporting and retention expectations for echo studies. [6]

Fix: Implement report templates that require a strain section whenever +93356 is billed and ensure images/measurements are stored and retrievable.

References

1. American Society of Echocardiography. Frequently Asked Questions -- Echocardiography Coding (Apr 2020). Authoritative echocardiography society coding FAQ used by echo labs and billing teams to operationalize add-on reporting and documentation expectations.
2. Anthem BCBS. Medical Policy -- Myocardial Strain Imaging (RAD.00068) (Jan 2026). Major payer medical policy describing coverage determinations and evidence thresholds that frequently drive denials for strain imaging.
3. Blue Cross Blue Shield of Kansas. Medical Policy -- Myocardial Strain Imaging (2024-2025 updates). Commercial payer policy illustrating common investigational/not medically necessary posture for broad routine myocardial strain imaging indications.
4. MVP Health Care. Provider Policy -- Echocardiography Coding (Oct 2024), excerpt on CPT 93356. Example of payer payment-policy logic that can deny +93356 as "global/bundled," distinct from investigational medical policy denials.
5. AMA CPT Assistant. Myocardial Strain Imaging (93356) (July 2020 issue). Authoritative AMA CPT guidance explaining the code's intent and how it functions as an add-on service when strain imaging is performed with echocardiography.
6. IAC Standards and Guidelines for Adult Echocardiography (Apr 2025). Accreditation standards widely used as a benchmark for echocardiography documentation, reporting completeness, QA, and image/data retention requirements.